Preclinical development of complex processing systems for ex vivo culture-expanded lymphohematopoietic cells, with subsequent immunologic and/or genetic manipulation, have been carried out in collaboration with a number of NIH institute investigators. o Preparation of allogeneic donor lymphocytes selectively depleted for alloreactive T-cells using an anti-CD25 immunotoxin (collaboration with NHLBI, Bench-to-bedside award): during this year, we completed development and scale up of this complex process, and in September 2001, initiated a phase I clinical trial of selectively depleted of donor-specific alloreactivity in the setting of allogeneic hematopoietic transplantation. o Preparation of donor Th2 T cells for clinical trials (collaboration with NCI): Development of this process incorporated CD8/CD20 depletion and CD3/CD28 bead stimulation, which produces a lymphocyte product that is 95% CD4+ and < 1% CD8+. The clinical trial was initiated in March 2001, and 9 patients have been treated to date (3 on dose level I, 6 on dose level II). Dose level III patients will be treated in early FY2002. o Fibronectin transduction: A method for improved gene transduction using fibronectin-coated bags was previously developed and incorporated into the clinical trial of gene therapy for chronic granulomatous disease. At the end of FY2001, this method was adapted to a new clinical trial of gene therapy in ADA deficiency that takes advantage of new vectors. To date, very high transduction efficiencies (>80%) have been observed.